PROJECT SUMMARY/ABSTRACT This competitive renewal application seeks to continue the longitudinal evaluation of children participating in the Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) study, an ongoing, prospective, randomized, controlled trial testing a responsive parenting (RP) intervention designed for the primary prevention of obesity versus a home safety control. In the US, 23% of 2-5 year olds are already overweight and 9% are already obese. By ages 6-11 years, 34% of US children are overweight and 17% are obese, highlighting the need for early life preventive interventions with sustained effects. With virtually no effective prevention approaches to date, we began INSIGHT by recruiting a birth cohort of 279 infants and parents who received four home visits during the first year after birth followed by annual clinic visits through age 3 years. The INSIGHT curriculum includes RP messages through age 2 years about infant feeding, sleep, interactive play, emotion regulation, and normal growth patterns; these areas were selected based on evidence linking them to obesity risk and their potential to be modified. Thus far, results from INSIGHT have been very positive: RP infants had lower mean weight-for-length at 1 year than controls and were less likely to be overweight at age 1 year (p<.05 for both). At age 3 years our primary outcome, body mass index (BMI) z- score, was significantly lower in the RP group than control (-0.13 vs. +0.15; p=.04). A multilevel model fit for the entire intervention period with a cubic time trend confirmed a main effect for intervention group (p=.0003). These results make INSIGHT the most successful early intervention trial for the prevention of childhood obesity to date. RP group children also have demonstrated improved sleep duration and behaviors, dietary content, and emotion regulation. INSIGHT has retained over 83% of participants through age 3 years, but the long-term effects of the RP intervention have not yet been assessed. The high rates of obesity among school age children in the US and the complete lack of existing early life primary preventive interventions with sustained effects form the scientific premise for this competitive renewal application, which proposes to test the sustained efficacy and long-term effects of our RP intervention on child BMI. Following attainment of annual growth measurements from participants from ages 5 through 9 years, we will use multilevel modeling to examine BMI growth curves from early childhood to age 9, and hypothesize that RP effects will persist across time points. We further expect that RP group parents will utilize more responsive parenting practices, and RP group children will exhibit greater self-regulation of eating behaviors (inhibitory control and appetite regulation), better sleep, more physical activity, and less sedentary behavior at the study's primary assessment point which occurs when participants are 6 years old.